Are natural dewormers effective?

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Stephanie's three-year-old filly.
Stephanie's three-year-old filly.

Q. I have a three-year-old Welsh/thoroughbred filly that was diagnosed last fall with liver disease. Our vets expected her to die within the month and told us there wasn’t anything to do.

Luckily, I come from a chiropractic family, and so with chiropractic adjustments and homeopathy my pony is alive and doing well.

I haven’t wormed her since her diagnosis because I know traditional wormers are hard on the liver. I was wondering if you know of a safe and effective natural dewormer. She is kept in a 12-acre field with seven other ponies. I board her and the other horses in her field are chemically dewormed.

Stephanie, Pennsylvania, USA

 

A.  Hi Stephanie,

Thanks for your question. There is much focus on naturally occurring dewormers these days.

The development of resistance to the commercially available dewormers has led scientists to test the effect of numerous plant, fruit, and fungal extracts. Many of these possess antiparasitic properties, and this has been found particularly pronounced for plants containing condensed tannins.

However, the application of these extracts in commercial products is not as straightforward as one might assume. All extracts need to be thoroughly tested for toxicity and safety profiles, which is costly. In addition, horses harbour many different parasite species, and the plant extracts are unlikely to be equally effective against all of them.

The concentration of the suspected active ingredients have turned out to be highly variable from extract to extract, so it is very difficult to ensure that the horse gets the needed dose level. Also, it has been found frequent and repeated treatment is needed to maintain satisfactory efficacy levels.

Steps to performing a fecal egg count.
Steps to performing a fecal egg count.

I have come across several commercial products marketed as natural dewormers over the years. I have many times requested documentation for these claims, but have never seen convincing evidence. Therefore, I am afraid I cannot give you any useful recommendations. My best suggestion would be to test the efficacy of the products you are using. Have your veterinarian perform fecal egg counts before and 14 days after deworming and calculate the percent egg count reduction.

It is worth mentioning that the most used commercial dewormer worldwide is ivermectin by a very large margin.

Ivermectin is per definition a natural dewormer, as it is produced by the naturally occurring fungus Streptomyces avermectilis. Like other dewormers, it has been thoroughly tested for safety and side effects, and there are no signs of liver affection.

Products labelled as “natural” could be just as toxic as anything else. If no safety and toxicity studies have been performed, there is no way to know if it is safe to give such products to your horse.

 

 

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Martin K Nielsen

Dr Martin Nielsen is an assistant professor in equine parasitology at the Maxwell H. Gluck Equine Research Center at the University of Kentucky. » Read Martin's profile

22 thoughts on “Are natural dewormers effective?

  • March 23, 2012 at 10:29 am
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    Hi – this isnt really a question/comment about “natural” de-wormers, but I remember when I was a kid in Australia we used to use the solid laundry “blue” stuff dissolved in the horses feeds as a wormer. Also when I was working for a racehorse trainer (30 odd years ago, and he was in his 70’s then!), he used to give each horse a minute, diluted IV dose of arsenic for blood worm (presumably strongylus vulgaris?). Is there any value in either of these that you know of?

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    • March 23, 2012 at 1:55 pm
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      Yes, historically lots of different remedies have been used for deworming horses. While some of these may have had some effect, most of them are likely to have been more harmful to the horse than the worms. I am not sure what the blue stuff in the laundry detergent was, but arsenic has been used for treating many different conditions over the years. It cannot be ruled out that it could have had some effect against Strongylus vulgaris, as one of the drugs currently available for treating heartworms in dogs is actually an arsenical. Examples of other “dewormers” used for treating horse parasites are soap, liquorice, tobacco leaves, linseed oil, chick or human faeces, eggs, guts of chicken or pigeons, and mercury.

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    • March 27, 2012 at 1:56 pm
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      I wonder if the solid laundry blue stuff was copper sulphate? I have used that in the past because improving copper levels can aid the general health of a horse and therefore it’s ability to handle a normal wormload. However there are safer, better absorbed products on the market so I’d rather get a blood test done before I treated for copper deficiency.

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      • March 29, 2012 at 5:29 pm
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        Yes, that is very possible. In the age before the modern dewormers, copper sulphate was used to treat parasites in livestock. It worked somewhat well, but was toxic to the animals, so people stopped using it when safer products became available. Today, copper oxide wire particles (COWP) have been found effective against the most important parasite of goats and sheep, the barberpole worm (Haemonchus contortus). COWP releases copper in a slower fashion, and is less toxic to the animals. These products have not been tested on horses, so I cannot recommend them.

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  • March 24, 2012 at 10:10 am
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    diatomaceous earth food grade work well but im not sure how it works on blood worms as it is not absorbed by the gut it only passes through the gut and kills the worms when they come in contact with the worms

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  • March 27, 2012 at 1:19 pm
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    We use diatomaceous earth as a natural wormer for all our horses and dogs, and since using this have always returned a zero egg count. It’s completely natural and harmless, as long as you get food-grade. It;s also used as a natural pesticide in vineyards, which is probably the easiest way to source it.

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  • March 27, 2012 at 1:47 pm
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    That’s interesting about ivermectin being a natural dewormer.
    Ivermectin is being touted in some vet publications and general commentary as being less effective than in previous times. Is this because the manufacturers of 3rd generation drenches want to sell more of their product or is ivermectin best used against certain worm families and less effective against others? Do you know of any genuine studies to measure the efficacy of ivermectin?

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    • March 28, 2012 at 2:33 pm
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      Yes, all the commercially available anthelmintic drugs are facing drug resistance to a smaller or larger extent, but this has nothing to do with the natural dewormer discussion.

      Since ivermectin was launched in the early 1980s, the pharmaceutical industry has not developed new drug classes for equine usage. So we are seeing increasing levels of resistance among the different parasites infecting goats, sheep, horses, and cattle. The solution is certainly not to use more of the same anthelmintics. Rather, the recommendation is now to reduce the treatment intensity and base the treatments on fecal egg counts.

      With the resistance now developing, we see the drugs losing efficacy against some parasites, while apparantly still working against others. So yes, a drug like ivermectin may still work, but maybe not against all the parasites it used to. There are loads of genuine studies published reporting the efficacy of ivermectin, and more are being published every year.

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  • March 27, 2012 at 2:03 pm
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    Thanks for pointing out that “natural” products may not necessarily always be proven safe and/or effective.

    What is your thought on the new fad of giving horses food-grade diatomaceous earth (DE) to kill internal parasites? DE is used in garden settings to kill insects. Some believe when ingested it kills worms in the gut. But I know one of the way DE works is that it shreds the exoskeleton of bugs on a microscopic level. Wouldn’t that do some harm to the sensitive and permeable lining of the intestines?

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    • March 28, 2012 at 2:37 pm
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      Thanks for your question. It is interesting how often I get asked about diatomaceous earth and its possible effect on parasites. I am not sure that this is particularly new, as I have heard about it for the past ten years. The few studies published in the scientific literature and the information I get from colleagues who have tried treating with diatomaceous earth, strongly suggest that it has no effect on the parasites. The proposed mechanism of action does not make any sense to me. Parasitic larvae survive well in soil layers, and I doubt that the “sharp” edges of the diatomaceous earth particles will disrupt the outer cuticle as proposed, unless the entire intestine is filled up with them. I am not aware of any safety and toxicity tests performed on horses, so I cannot answer your question regarding potential side-effects for the horse.
      Until we see some convincing evidence documenting an efficacy of diatomaceous earth against parasites, I would not consider it useful for this purpose.

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      • July 17, 2012 at 2:14 am
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        I am all for homeopathy, because that is what brought me back from a bad head injury. However, for three years I had four horses on diatomaceous earth, and all four developed ulcers. I am back to using regular worming methods.

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  • March 28, 2012 at 3:34 am
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    Dr. Nielson,
    My holistic vet also gives nosodes along with the fecal egg counts to do. Your thoughts for suggesting this?
    Pam

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    • March 29, 2012 at 5:29 pm
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      There is very little scientific evidence for homeopathic treatment of parasites, but a few studies suggest some effect. For nosodes I have not seen any studies investigating effects against worms. All in all, more research is needed to evaluate the potential for homeopathy in parasite control.

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  • March 28, 2012 at 3:47 am
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    Hi Dr. Nielsen,
    You say some products labelled as “natural” could be just as toxic as anything else. If no safety and toxicity studies have been performed, there is no way to know if it is safe to give such products to your horse.

    Can you give a couple of examples, please?

    The products I see say natural, herbal, etc..

    Reply
    • March 28, 2012 at 2:28 pm
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      Generally, when a product is marketed as a feed additive (as opposed to medicine), the requirements for testing and documentation are much less stringent. This goes for most of the herbal, natural products. Generally, the risk of these products being toxic is very small, but the chance of them killing parasites at a significant level is equally small. My point was that the words “natural, herbal” etc do not automatically equate less toxic.

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  • March 30, 2012 at 3:51 pm
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    Fantastic that your pony is better. She looks lovely. However, please don’t place too much confidence in homeopathy, as it really does not work for any condition whatsoever. I’m not aware of any good research that says chiropractic works for animals either.

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    • April 19, 2012 at 11:49 am
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      Hi Andrew Gilbey. I sincerely trust your comment “I’m not aware of any good research that says chiropractic works for animals either.” refers to de-worming only. There is ample evidence to prove that Chiropractic on horses is beneficial. My yearling with bizarre ‘head sweats’ (suggested by 3 vets as due to comprimised or damaged sympathetic nerve) had a Chiropractic Equine Vet work on him, and was immediately symptom free! (with 6 monthly manipulations as maintenance). As an aside -can you refer me to any studies/research papers on diatomaceous earth deworming horses. Also, would there be any possiblity of D.E. causing enteroliths? Cheers.

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      • October 29, 2013 at 3:37 pm
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        Hi Anita,

        To be quite honest, I was actually referring to chiropractic for animals per se. Research for the benefits of chiropractic on humans is far from convincing (in my opinion). I am of the opinion that the same goes for animals.

        Are you aware of how chiropractic was ‘invented’? (It was by a grocer with no education – beginning to se where this is going?) Some of their beliefs for how the [human] body works beggar belief! For example, some chiropractors seem to think they can ‘cure’ infertility.

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  • April 7, 2012 at 2:44 am
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    slight overdoses of herbal such as the wormwood , blackwalnut , etc -can cause death very , very fast – the wormwood is more toxic than the usual tablets. the lymph packs up , you have to spend hundrweds over years to reduce the swellings & remove the toxins etc plus wars with the vets & eventually have to consult miracle healings.
    several remedies can be used to heal the toxic effects , very expensive & more than 1 year.
    DE is great , but at forst much more worms come out – you have to go through this & at least 70-90 days during summer r whatever plus DE does not kill the larvae of tapeworm.
    if you can remove & prevent worms altogether -giovt agents & docs force worms into your dogs to make money & thpse worse or worse occult worms.
    always give lots of Milklthistle, probiotics , flax oils , & spirulina & other various supplements to re-grow the liver , kidneys, etc.

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  • July 4, 2015 at 12:05 am
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    I use food grade diatamaceaous earth, Apple cider vinegar, garlic and marshmallow root. Then we fecal test had my horse 2 years have Only had to worm her once when I first got her. There are many ways to get around using nasty chemical wormers. Some of the things I’ve mentioned also aid in digestion and help with ulcer prevention.

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    • July 4, 2015 at 12:11 am
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      Also, chiropractic care is fantastic as far as adjustments go. Two lameness vets had my niece convinced her gelding was arthritic, had stifle issues and needed injections plus supplements. I said no way called chiropractor. She came out 3-4 Times adjusted him he’s been fine ever since. The issues he was having stemmed from back being out of alignment. The gelding was only 10 I can’t imagine giving him unneeded injections. Ridiculous

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  • July 29, 2015 at 2:26 am
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    GIVE YOUR ANIMALS A TABLESPOON OF GARLIC POWDER PER WEEK ON THEIR FEED.AND BY THE 2ND.DAY NO MORE PARASITES.

    Reply

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